Telephone system



Jan. 23, 1934. E. s. PETERSON 1,944,594

TELEPHONE SYSTEM I Filed July 18, 1932 2 Sheets-Sheet l R & :Q

dward 5. Pm

Jan. 23, 1934. E, s, PETERSON TELEPHONE SYSTEM Filed July 18. 1952 2Sheets-Sheet 2 -l'1mlfi Edward 5P2 arson Patented Jan. 23, 1934 UNITEDSTATES PATENT OFFICE TELEPHONE SYSTEM Application July 18, 1932. SerialNo. 623,083.

20 Claims.

The present invention relates in general to telephone systems, but isconcerned more particularly with operator controlled magneto exchange(O. C. X.) telephone systems, in whichcommunications between twosubscribers are established by manual operators from a remote or distantcontrol point.

More in particular, the present invention rev lates to a telephonesystem wherein an operator at a central office may control the switchingequipment in an outlying exchange or rural office terminating localbattery magneto lines either to establish connections between twosubscribers in the rural oflice or to establish connections to thecentral or main oflice.

One object of the invention is to provide a cheap but neverthelessefficient unit for small rural communities that heretofore have beenwithout any communicating service because the number of subscribersdesiring service did not warrant the installation of a switchingexchange.

The switching unit in the present invention is arranged to take care often subscribers lines and is controlled over a single trunk line from adistant central ofiice by a manual operator. The switching unit mayeasily be mounted in an iron box and mounted on a telephone pole at thecentral point in the community to be served. The unit operates on a12-volt storage battery that is floated by the distant central ofiicebattery over the trunk line. The operator in the manual exchangetransmits ringing current over the trunk line to signal the callingsubscriber if necessary and also to signal the wanted subscriber.

Another object of the invention is the provision of improved circuitarrangements, whereby the control of the magneto exchange by theoperator at the central oflice may be brought about in a thoroughlyreliable manner, while the numher of conductors required between the twoexchanges over which the operator controls the setting up of connectionsbetween subscribers in the magneto exchange is reduced to a minimum.

Description of drawings ring now to the drawings, they show by meansofthe switching equipment shown to the left of the trunk line TL in Fig.2 comprises the operator controlled magneto exchange. The local batterymagneto substations T1 and T2 terminate in the finder switch FS which isoperated to find a calling subscribers line. The. connector switch CS,which is part of the operator controlled exchange equipment, isdirectively positioned by impulses from the manual exchange operatorsposition to select a wanted subscribers line. The finder switch FS andthe connector switch CS are of'the well-known rotary type whose wipersare advanced upon the release of their respective stepping magnets. Fig.2 shows the equipment in the manual exchange and comprises the operatorstrunk circuit TC, the answering jack J, the operators cord circuit CC,and the calling device CD by means, of which the operator at. the manualexchange controls the switching equipment in the operator controlledexchange by plugging in jack J1.

Detailed description A detailed description of the operation of theapparatus shown will now be given. It will be assumed that thesubscriber at substation T1 desires'to establish a connectidn with thesubscriber at substation T2.

The subscriber at substationv T1 in order to signal the operator at themanual exchange, operates his handzgenerator to transmit ringing currentover his line, after which he removes his receiver so as to be able toconverse with the operator when she responds. Responsive to the ringingcurrent transmitted .over line conductors 1 and 2, relay 3 operates andcompletes a locking circuit for itself at armature 6 and its frontcontact. Relay 3 remains locked in its energized po-' sition until theoperator answers the call. At armature '7 and its front contact, therelay 3 grounds the common start conductor 76 thereby causing theenergization of start relay 1'1 and at armature 5 and its front-contactgroundsa bank contact of the finder switch FS to mark the-calling line.

It may be well to mention at this time that if some other subscriberinthe O. C. X. has previously initiated a call, the finder switch FSwill not be available for extending the call from SUbSlifl'? tion T1 tothe operator at the manual exchange. However, when the switchingequipment in the O. .C. X; is released by the calling subscriber, thefinder switch will immediately operate, since the relay 11 will bemaintained energized from the ground at armature '7 of the line relay3and-:will

hunt for the line marked by ground at armature 5 and its front contacts.

It will be assumed, however, that the equipment in the operatorcontrolled exchange is idle. As soon as start relay 11 is operated, itcloses a circuit at armature 23 and its front contact for the rotarymagnet 8 of the finder switch FS. The circuit for operating rotarymagnet 8 is as follows: battery, winding of magnet 8, armature 23 andits front contact, armature 27 and its resting contact, armature 45 andits resting contact, conductor 67, armature 111 and its resting contact,to ground. At armature 74 and its front contact, magnet 8 completes anenergizing circuit for the upper winding of relay 13 which responds andat armature 27 and its resting contact opens the initial energizingcircuit for the magnet 8. The magnet 8 deenergizes, thereby advancingwipers 5457 one step into engagement with the next set of bank contacts,and at the same time opens the circuit for the upper winding of relay 13at armature 74 and its front contact. If the bank contacts encounteredby the wipers 5457 are not the contacts to which the line of substationT1 is connected, magnet 8 will again energize, as soon as relay 13 fallsback, over. the previously traced circuit. The interaction betweenmagnet 8 and relay 13 continues and the wipers 54-57 are advanced eachtime the circuit of the magnet 8 is opened until the wiper 55 encountersthe bank contact marked by the opera tion of the calling subscribersline relay. When this occurs, the following circuit is completed fromground, armature 5 and its front contact, wiper 55, conductor 65,armature 110 and its resting contact, conductor 64, lower winding ofrelay 20, 'lower winding of relay 13, to battery. Relay 13 is maintainedenergized over this circuit to prevent further rotation of the wipers ofthe finder switch FS. Relay 20 energizes and completes a locking circuitfor itself over its upper winding over a circuit from battery, upperwinding of relay 20, armature 47 and its front contact, armature 40 andits resting contact, to ground. At armature 46 and its front contact,relay 20 closes a circuit from ground, armature 40 and its restingcontact, armature 46 and its front contact, conductor 68, armature 112and its resting contact, winding of slow-to-release relay 104, tobattery. Relay 20 opens another point in the circuit for magnet 8 atarmature 45 and its resting contact, it short circuits the lower orholding winding of line relay 3 over a circuit including armature 44 andits front contact and wiper 56 of the finder switch FS, thereby causingthe line relay 3to restore to normal, it prepares a circuit for relay 22at armature 43 and its front contact, and at the front contacts ofarmatures 42 and 48 it extends the calling subscribers line overconductors 62 and 75, respectively, to the left-hand winding ofrepeating coil R. Responsive to the restoration of line relay 3, theupper winding of the relay is again bridged across the callingsubscribers line conductors 1 and 2, and at armature 7 and its frontcontact the operating circuit for start relay 11 is opened.

It should be noted that relay 102 in the O. C. X. is energized in serieswith relay 122 in the manual exchange over a circuit including the24-volt manual exchange battery, the two conductors of the trunk line TLin parallel and the 12-volt O. C. X. battery. Responsive to theoperation of relay 104, the battery charging circuit of the O. C. X.which includes the winding of relay 102 isopened at armature 114 and itsresting contacts. Relay 102 in the O. C. X. and relay 122 in the manualexchange deenergize. Relay 102 upon falling back closes an energizingcircuit for relay 103 as follows: from battery, winding of relay 103,armature 106 and its resting contact, conductor 69, armature 40 and itsresting contact, to ground. At armatures 109 and 113 and theirrespective front contacts, relay 103 extends the conductors 115 and 116of the trunk line TL to the right-hand winding of the repeating coil Rand at the same time additional points in the charging circuit areopened at the normally closed contacts controlled by armatures 109 and113 and their respective front contacts. At armature 112 and its restingcontact, relay 103 opens the circuit for the S10W- to-release relay 104which upon restoring again prepares a circuit for relay 102 at armature114 and its resting contact. At armature 111 and its resting contact,relay 103 opens an additional point in the circuit for magnet 8, and atarmature 110 and its front contact it prepares a circuit for relay 22.The closing of armature 107 and its resting contact, and the opening ofarmature 108 and its front contact by the release of relay 102 has noeffect at this time.

Referring now to relay 122 in the manual exchange which falls backresponsive to the operation of relay 104 in the O. C. X. As soon asrelay 122 falls back, it completes a circuit at armature 134 and itsresting contact for energizing relay 123. At armature 137 and its frontcontact, relay 123 completes a locking circuit for itself and at thenormally closed contacts controlled by the front contacts of armature137 it opens its initial energizing circuit. At armature 136 and itsresting contact, relay 123 disconnects relay 122 from the trunkconductors and at armature 138 and its front contact it completes acircuit for lighting the calling lamp L to signal the operator at themanual exchange. In addition, a circuit is completed to a delay alarmcircuit,

which starts to function and gives the operator an audible signal if shedoes not answer the call Within a predetermined interval of time.

When the operator at the manual exchange notes the lighted lamp L, sheinserts the plug of her cord circuit CC into the answering jack J.Responsive to the plugging in at the answering jack J, contacts 139 ofthe jack springs are closed thereby completing an energizing circuit forrelays 118 and 120. Relay 119 operates responsive to the energization ofrelay 120. At armature 127 and its front contact, relay 118 places ashunt around the condenser in the righthand winding of the repeatingcoil R1 thereby preparing the supervisory circuit in the cord circuitCC. At armature 126 and its front contact, relay 118 prepares a circuitfor connecting battery by way of the impedance 121 and the normallyclosed contacts controlled by armature 135 to the upper trunk conductor,and at armature 12S and its front contact, it prepares a circuit forconnecting battery by way of relay 117 and ringing key K2 to the lowertrunk conductor.

Referring again to the operation of relay 119. At armature 130 and itsresting contact, relay 119, opens the locking circuit for relay 123, at

armature 131 and its front contact it opens the circuit to the delayalarm circuit, at armatures 129 and 140 and their respective frontcontacts it connects battery from the impedance 121 to the upper lineconductor and connects battery from relay 117 to the lower lineconductor. At the resting contacts of armatures 129 and 140, additionalpoints in the charging circuit are disconnected. The calling lamp L isextinguished responsive to the deenergization of relay 123.

When battery is connected to the upper trunk conductor by the operationof relay 119, the following circuit is closed; from battery, winding ofimpedance 121, armature 126 and its front contact, normally closedcontacts controlled by armature 135, armature 129 and its front contact,upper left-hand winding of repeating coil R1, conductor 115 of trunkline TL, armature 109 and its front contact, upper right-hand winding ofrepeating coil R, conductor 72, winding of relay 16, to ground. Whenbattery is connected to the lower trunk conductors by the operation ofrelay 119, the following circuit is closed; from battery, relay 117,armature 128 and its front contact, normally closed contacts of key K2,armature 140 and its front contact, lower lefthand winding of repeatingcoil R1, conductor 116 of the trunk line TL, armature 113 and its frontcontact, lower right-hand winding of repeating coil R, conductor 70,armature 28 and its resting contact, armature 53 and its restingcontact, conductor 71, winding of relay 101 to ground. Relay 16energizes in series with impedance 121,

and relay 101 energizes in series with relay 117.

At armature 125 and its resting contact, relay 117 opens a point in thesupervisory circuit ofthe operators cord circuit CC and relay 101 opensa point in a signalling circuit at armature 105 and its resting contact,the function of which will be explained hereinafter. Relay 15 operatesresponsive to the operation of relay 16 and prepares a circuit for themagnet 9 of the connector switch CS at armature 32 and its frontcontact, prepares a circuit for relay 18 at armature 33 and its frontcontact, operates relay 19 over a circuit including armature 31 and itsfront contact, and at armature 30 and its front contact maintains theconductor 69 grounded. At armature and its resting contact, relay 19opens a point in the circuit for grounding conductor 69 which is nowmaintained grounded from armature 30 and its front contact, and atarmature 41 and its front contact it completes a locking circuit foritself over conductor 73 to ground at armature 107 and its restingcontact.

If the subscriber at substation T1 has removed his receiver and haswaited for the operator at the manual exchange to respond, thesubscriber may now converse with the operator at the manual exchange.The operator at the manual exchange may either extend the connection forthe subscriber at substation T1 to a wanted subscriber in the manualexchange or if the subscriber at the substation T1 desires to talk toanothersubscriber connected to the O. C. X. the operator dials back overthe trunk to set the connector switch C5 to the wanted subscribers line.

If the subscriber at substation T1 has not removed his receiver, theoperator at the manual exchange may signal the subscriber by operatingher ringing key K. The circuit operation that takes place when theoperator signals a subscriber that has initiated a call will now bedescribed.

When the operator at the manual exchange operates her key K2, thecircuit over conductor 116 of the trunk line TL that includes thewinding of relays 117 and 101 is opened at armature 125and its restingcontact. Relay 117 falls back and again closesthesupervisory circuitinthe operators cord circuit CC, and relay 101 upon falling backprepares a circuit for the A. C. relay 14 at armature 105 and itsresting contact. At the front contact of the key K2, ringing current isconnected to the lower line conductor 116 to operate the A. C. relay 14in the O. C. X. over the following circuit: from battery, generator GEN.front contact of key K2, armature 140 and its front contact, lowerleft-hand winding of the repeating coil R1, conductor 116 of the trunkline TL, armature 113 and its front contact, lower right-hand winding ofthe repeating coil R, armature 105 and its resting contact, conductor63, winding of A. C. relay 14, condenser, to ground. At armature 28 and.its resting contact, A. C. relay 14 relays a point in the circuit ofrelay 101, and at armature 29 and its front contact, completes anenergizing circuit for relay 21. The opening of the resting contacts ofarmatures and 51 by relay 21 has no effect at this time. At armature 49and its front contact, relay 21 connects the upper line conductor of thecalling subscribers line to the conductor 63 over which the ringingcurrent is being transmitted, and at armature 52 and its front contactgrounds the lower line conductor of the calling subscribers line. Theringing current is now transmitted by way of armature 49 and its frontcontact, armature 42 and its front contact, Wiper 54 of the finderswitch FS, armature 4 and its'resting contact, upper winding of the linerelay 3, wiper 57 of the finder switch FS, armature 48 and its frontcontact, armature 52 and its front contact, to ground. Line relay 3 ofthe calling subscribers line energizes over this circuit and completes alocking circuit for itself at armature 6 and its front contact, and atarmature 5 and its front contact, grounds conductor by way of wiper 55of the finder switch FS. At armature 4 and itsresting contact, linerelay 3 disconnects its upper winding from across the line conductors 1and 2, thereby removing the short across the line conductors so that theringing current now operates the bell at the subscribers station.

The operator restores the ringing key K2 to its normal position afterthe ringing current has been transmitted over the trunk line for a shortinterval thereby causing the A. C. relay 14 to restore to normal, whichrelay in turn opens the circuit for relay 21 and at armature 28 and itsresting contact it again prepares the circuit for relay 101. Relay 21falls back and at armatures 49 and 52 and their respective restingcontacts extends the calling subscribers line over conductors 62- and tothe upper lower left-hand windings of the repeating coil R. Relay 21also shunts the holding winding of the subscribers line relay 3 and itrestores to normal. In the manual exchange relay 117 operates in serieswith relay 101 in the O. C. X. over the previously traced circuitincluding the conductor 116of the trunk line TL. The subscriber removeshis receiver after being signalled by the operator and informs theoperator at the manual exchange of' the number of the wanted subscriber.

The description of the operation of the circuit when it is necessary forthe operator to call a subscriber that has initiated a call iscompleted. It maybe well to point out, however, that the feature ofpermitting a subscriber that originatesa call to hang up his receiver,leaving his line relay locked up, has been included because only oneconnection can beestablished at a time.

Therefore, if the subscriber originates a call whenv change.

the single trunk line is busy, he need not make several attempts to getthe operator because his call will be locked in and when the trunk lineis available the finder will pick up his line and sig- ,nal the operatorwho will ring-back over the line to signal the calling subscriber.

The description of the operation of the circuit about to be given is thesame whether the subscriber at substation T1 removed his receiver andwaited for the operator to respond to his call or if he did not removehis receiver and waited for the operator to signal him.

When the operator at the manual exchange receives the number of thewanted subscriber, for example the subscriber at substation T2, sheplugs her dialling cord DC into the dial jack J1 and manipulates thecalling device CD in accordance with the number of the wantedsubscribers line. As soon as the calling device is moved from its normalposition, a circuit is ciosed from ground at the off-normal spring inthe calling device CD, tip of the plug in jack J1, winding of relay 124,to battery. Relay 12 1 operates and at normally closed contactscontrolled by armature 135 disconnects the impedance 121 from the upperline conductor, and connects battery by way of the impulsing springs ofa calling device CD and the sleeve of the plug and jack J1 to the upperline conductor. It should be noted, that relay 16 in the O. C. X. is nowenergized from battery at the interrupter springs of the calling deviceCD over conductor 115 of the trunk line TL instead of from battery atthe impedance 121 in the manual ex- As the calling device CD is restoredto normal, the circuit of relay 16 is interrupted by the opening andclosing of the interrupter springs of the calling device CD. Each timerelay '16 falls back responsive to the momentary opening of its circuit,a circuit is closed from ground, armature 34. and its resting contact,armature 32 and the front contact, over one path including the windingof the slow-to-release relay 12, to battery, and over another paththrough the winding of the magnet 9 of the connector switch C6, tobattery. The slow-to-release relay 12 will remain energized throughoutthe series of impulses transmitted to the rotary magnet 9 by themomentary deenergization of the relay 16. Each time relay 16 isenergized again responsive to a momentary closure of the interruptersprings of the calling device CD, relay 15 receives another charge ofcurrent to maintain it in its energized condition throughout the seriesof impulses. Each time the circuit of the rotary magnet 9 is opened, themagnet deenergizes and advances the wipers 5861 one step. On the firstrotary step of the wipers 586l, the off-normal springs 24 are closed.However, the closure of the oif-normal springs 24 has no effect at thistime because the slow-to-release relay 15 is maintained energized. Eachtime the impulsing relay 16 momentarily falls back and closes theabove-mentioned circuit for therotary magnet, the magnet energizes andresponsive to the reenergization of the relay 16, the circuit of themagnet 9 is opened, thereby advancing the CD. It should be noted thatthe ring contact of V the dialling cord DC is grounded in order tomaintain relays 120 and 118 energized if the operator should desire toremove her cord circuit CO from the answering jack J After the rotarymagnet has been operated by impulses transmitted by the relay 16, thefollowing circuit is completed in series with the rotary magnet:battery, winding of magnet 9, self-interrupting contacts at the end ofthe rotary magnet 9, off-normal springs 24, (closed on the first rotarystep of the wipers 58-61) armature 33 and its front contact, winding ofrelay 18, to ground. Relay 18 energizes over this circuit but the rotarymagnet does not. At armature 39 and its front contact, relay 18 preparesa circuit for relay 17.

When the operator has finished dialling, she operates her ringing key K2in the same manner previously described, thereby transmitting ringingcurrent over the trunk conductors to operate the A. C. relay 14 in theO. C. X. At armature 28 and its resting contact, A. C. relay 14 opens apoint in the circuit of relay 101 and at armature 29 and its frontcontact, completes an energizing circuit for relay 17.

The opening of the resting contacts of armatures 37 and 38 by relay 1''!has no effect at this time. At armature 35 and its front contact, relay17 connects the upper line conductor 1".of the called subscribers lineto the conductor 63 over which the ringing current is being transmitted,and at armature 36 and its front contact grounds the lower lineconductor 2' of the called subscribers line. The ringing current is nowtransmitted by way of armature 35 and itsv front con tact, wiper 58 ofthe connector switch CS, conductor 1', armature 4' and its restingcontact, upper winding of line relay 3', conductor2, Wiper 61 of theconnector switch CS, armature 25v and its resting contact, armature 36and its front con tact, to ground. Line relay 3 of the calledsubscribers line energizes over this circuit and it closes a lockingcircuit for itself at armature 6' and its front contact, and at the sametime it removes the upper winding from across the line conductors 1' and2'. When the upper winding of relay 3 is disconnected from theconductors of the wanted subscribers line, ringing current is projectedover conductors 1 and 2' to ring the bell at substation T2.

When the ringing current is transmitted to signal the wanted subscriber,the current flowing in the right-hand winding of. the repeating coil Rinduces a current flow in the left-hand winding of the coil over thecalling subscriber's loop circuit thereby giving the calling subscriberan indication or tone signal indicative of the factthat theoperator. issignalling'the wanted subscriber.

The operator at the manual exchange restoresthe ringing key K2 to itsnormal position after the subscriber at substation T2 has beensignalled. When the ringing is disconnected from the -conductor 116 ofthe trunk line TL at the front contact of key K2, A. C. relay 14restores to normal and again prepares the circuit for relay 101 atarmature 28 and its resting contact, and at armature 29 and its frontcontact opens the circuit for'relay 17 which accordingly falls back..At'

the resting contact controlled byarmatures 35 and 36, relay 17 extendsthe wanted subscribers line by way of the front contacts of armatures 42and 48 to the line conductors of the calling subscribers line. Atarmature 38 and its resting contact, relay 17 closes a circuit by way ofthe wiper 60.for short-circuiting the lower holding winding of relay 3'thereby causing line relay 3' to restore to its normal position. Whenthe resting contact of the ringing key K2 is closed, relays 117 and 101energize again over the previously traced circuit.

When the subscriber at substation T2 removes his receiver theconversation between the subscriber at substations T1 and T2 can nowtake place. The talking circuit is as follows: from station T1,conductor 1, wiper 54 of the finder switch FS, armature 42 and its frontcontact, armature 35 and its resting contact, wiper 58 of the connectorswitch CS, conductor 1', of station T2, conductor 2, Wiper 61 of theconnector switch CS, armature 25 and its resting contact, armature 36and its resting contact, armature 48 and its front contact, wiper 57 ofthe finder switch FS, conductor 2, to the subscriber at substation T1.

The operator at the manual exchange will hold the trunk so that she maysupervise the call and release the connection when the subscribers giveher the usual disconnect signal when they ringoff.

When the conversation is completed the subscribershang up theirreceivers and operate their hand generators to transmit ringing currentover their lines and line relays 3 and 3' operate. It should-be notedthat the holding winding of relay 3 is short-circuited from ground atarmature 51 and its resting contact. Therefore, the relay will chatterresponsive to the ringing current but the lightly adjusted armature 5and its front contact remain closed as long as current is on the line.Line relay '3 operates in the same manner as line relay 3 and isshort-circuited fromground at armature 26 and its resting contact. Atarmature 5 and its front contact, relay 3 closes a circuit from ground,armature 5 and its front contact, wiper 55 of the finder switch FS,conductor 65, armature 110 and-its front contact, conductor 66, armature50 and its resting contact, armature 43 and its front contact, windingof relay 22, to battery. A circuit is also completed by line relay 3'from ground, armature 5 and its front contact, wiper 59 of the connectorswitch CS, armature 37 and its resting contact, winding-of relay 22, tobattery. Relay 22 energizes over either of these circuits and atarmature 53 and its resting contact opens the series circuit, over thelower trunk conductor, or relays 101 and 117. The falling back of relay101 has no efiect at this time. The falling back of relay 117 completesa circuit at armature 125 and its resting contact for giving the manualexchange operator disconnect supervision.

It should be noted that relay 22 maintains the series circuit of relays101 and 117 open only as long as the subscribers operate their handgenerators. Therefore, relay 22 falls back and again completes thecircuit for relays 101 and 117 when the subscriber stops turning thehand generator.

When the manual operator receives the disconnect signal, she will removeher dialling cord DC and her calling cord CC from the jacks J1 and J 2,respectively. When ground is removed at contact 139 of the answeringjack, relays 118 and 120 restore to normal. Slow-to-release relay 119falls back responsive to the deenergization of slow-torelease relay 120.Relay 118, however, falls'back immediately and at armature 128 and itsfront contact opens the circuit for relays 117 and 101. At armature 126and its front contact, relay 118 opens the series circuit over the uppertrunk conductor 115 which includes impedance 121 in the manual exchangeand relay l6 in'the O. C. X. Relay l6 deenergizes and opens the circuitof relay 15 which also falls back with slow-action. At armature 30 andits front contact, relay 16 opens the locking circuit of relay 103 andrelay 20. Relays 20 and 103 restore to normal. At armatures and 43 andtheir respective front contacts, relay 25 disconnects the calling andthe called subscribers lines. The restoration of relay 103 to its normalposition prepares a circuit for relay 102 from the 12-volt O. C. X.battery, winding charging relay 102, armature 114 and its restingcontact, the normally closed contact controlled by armatures 109 and 113of relay 103, over conductors 115 and 116 of trunk line TL, to armatures129 and 140. As soon as slow-to-release relay 119 restores to normal thecircuit of relay 102 is extended by way of the resting contacts ofarinatures 129 and 140, armature 136 and its resting contact, winding ofthe charging relay 122 in the manual exchange, normally closed contactsof key Kl, charge-control rheostat CCR to the 24-volt manual exchangebattery. Relays 102 and 122 operate over this circuit. The operation ofrelays 102 and 122 will be described more in detail hereinafter. Atarmature 1'34 and its resting contact, relay 122 opens a point in thecircuit of relay 123. v

Referring again to the release of relay 16 in the O. C. X. At armature34 and its resting contact, relay 16 completes an energizing circuit forthe rotary magnet 9, and slow-to-release relay 12. When thesloW-to-release relay 15 falls back it opens the circuit, for thejmagnetthereby causing it to release and advance its wipers to the next step;Relay 12 remains energized for a short interval due to its slow actionand at armature 26 and its resting contact removes ground from wiper'60so that any line relays that are locked up will not be shunted down asthe connector restores its wipers to normal. At armature 33 and itsresting contact, relay l5 completes a selfinterrupting circuit for therotary magnet 9 by way of the ofI-normal contacts 24 and theselfinterruptingcontacts 10 of the rotary magnet 9. The rotary magnetcontinues to operate and interrupt its own circuit until the wipers ofthe switch are restored to their normal position, at which position theoff-normal springs 24 are opened thereby bringing the wipers of theswitch to rest. The equipment in the O. C. X. is now restored to normaland will respond to extend a connection to the operator at the manualexchange when the subscriber initiates a call.

Charging of the battery at the operator controlled exchange I It will benoted that there are several battery symbols in the O. C. X. eachindicating a battery with a positive pole grounded and the negative polefree. It should be understood, however, that these symbols represent thesame battery. It will also be noted that several battery symbols shownin the manual exchange, each indicating a battery with the positive polegrounded and the negative pole free. Each of these symbols r present thebattery in the manual exchange. The manual exchange battery has avoltage of approximately twenty-four volts and is the regular exchangebattery, whereas the battery in the O. C. X. is approximately twelvevolts. When the equipment in the O. C. X. is not in use, current isnormally flowing from the battery in the manual exchange by way of thecharged control rheostat CCR, normally closed contact of key K1, windingof relay 122, and armature 133 and resistance 130 in parallel with thewinding of relay 122, armature 136 and its resting contact, the twoconductors 115 and 116 of the trunk line TL, resting contacts ofarmatures 129 and 140, respectively, upper and lower left-hand windingsof the repeating coil R1, normally closed contacts controlled byarmatures 109 and 113, armature 114 and its resting contact, over onepath including the winding of relay 102 to battery in parallel with thecircuit including armature 107 and its front contact and resistance 141to battery. It should be noted that relays 102 and 122 are maintainedenergized over this circuit and that the resistances 140 and 1 11 areshunted around the windings of relays 122 and 102, respectively,toprevent the relays from becoming overheated due to the continuouscurrent flow over the circuit. It is evident from the foregoing that thebattery in the O. C. X. is floated over the trunk line by the manualexchange battery. Key K1 is provided for disconnecting the chargingcircuit from the manual exchange battery to the O. C. X. battery and forconnecting ground to relay 122 for the purpose. of maintaining therelays 122 and 102 energized so that the manual exchange operator can besignalled when an O. C. X. subscriber desires to make a call.

Call from manual exchange subscriber to O. C. X. subscriber If asubscriber in the manual exchange desires to converse with thesubscriber in the O. C. X. the operator at the manual exchange willextend the connection by plugging in her cord circuit into the jack J.Relays 118 and 120 are energized from contacts 139 of the jack J. Relay119 operates responsive to the operation of relay 120 and at the restingcontacts of armatures 129 and 140 disconnects the charging circuitcausing the release of relay 122 in the manual exchange and relay 102 inthe O. C. X. At the front contacts of these armatures, battery isconnected to the upper line conductor from impedance 121 and battery isconnected to the lower line conductor by way of relay 117. In the O. C.X. relay 102 upon falling back, causes the energization of relay 103 ofarmature 106 and its resting contact. At armatures 109 and its frontcontact, relay 103 extends battery from the impedance 121 over theconductor 115 of the trunk line TL, armature 109 and its front contact,conductor '72, winding of relay 16 to ground. At armature 113 and itsfront contact, relay 103 extends battery from relay 117 over the lowertrunk' conductor 116, armature 113 and its front contact, conductor '70,armature 20 and its resting contact, armature 53 and its restingcontact, conductor 71, winding of relay 101 to ground. Relay 16 in theO. C. X. energizes and relay 101 in the O. C. X. energizes in serieswith relay 117 in the manual exchange. Relay l5roperates responsive tothe operation 'of relay 16 and prepares the connector switch CF in theO. C. X. for operation.

The operator in the manual exchange may now position the connectorswitch CS to the wanted subscribers line, which in this case is assumedto be the line of the subscriber at substation T2. The operation of thecircuit is the same as has been described hereinbeicre. Therefore, itWill suffice to say that the operator dials over the trunk and positionsthe connector CS to the line of substation T2 and operates her key K2 tosignal the subscriber at substation T2. When the subscriber removes hisreceiver the subscriber at the manual exchange and the subscriber atsubstation T2 can converse. When the conversation is completed thesubscribers hang up their receivers and the subscriber at substation T2rings off in the same manner described hereinbefore to give the manualexchange operator disconnect supervision.

The operator at the manual exchange removes her cord circuit CC, andrelays 118 and 120 in the trunk circuit fall back. At armature 126 andits front contact, relay 118 removes battery from the upper trunkconductor 115, thereby causing the release of relay 16 in the O. C. X.exchange. Relay 15 also falls back and at armature 33 and its restingcontact completes a circuit for the magnet 9 which interrupts its owncircuit, thereby advancing the wipers 5851 to their normal home positionat which position, off-normal contacts 24 are opened to stop the rotaryaction of the magnet 9.

Relay 103 in the O. C. X. is released responsive to the deenergizationof relay 15. At the normally closed contacts controlled by the frontcontacts of armatures 109 and 113, relay 103 again connects up thecharging circuit in the O. C. X. and at the resting contacts ofarmatures 129 and 140, relay 119 connects up the charging circuit in themanual exchange. Relay 192 and relay 122 energize as before to completethe charging circuit.

What is claimed is:

1. In a combined manual and operator controlled telephone system, atrunk line extending from the manual exchange to the operator controlledexchange, a finder switch and a connector switch in the operatorcontrolled exchange permanently connected with said trunk, meanscontrolled over a calling line for operating said finder to connect thetrunk line with the calling line, an impulsing relay in the operatorcontrolled exchange controlled over one conductor of said trunk linefrom the manual exchange to set the connector switch on the contacts ofa desired called line to complete a desired connection.

2. In a telephone system, an automatic connector switch having normallyconnected wipers, means under control of a calling party fortransmitting impulses to said switch to advance the Wipers intoengagement with contacts of the desired line, an alternating currentrelay in said switch, said relay operated responsive to the applicationof ringing current to said connector, and means controlled by said relayfor connecting a branch circuit over which the ringing Eu? rent istransmitted to signal the subscriber on said line.

3. In a telephone system, a finder switch accessible to a plurality oflines and arranged to stand normally in any arbitrary position,aconnector switch having access to the same plurality of lines, anoperators position, means responsive to the initiation of a call by asubscriber on one of said lines for operating said finder to find saidline and for signalling the operator, means controlled by the operatorfor operating the connector switch to select the wanted subscribers lineand for signalling the wanted subscriber on the line, means controlledby the subscribers after they hang up their receivers for giving theoperator disconnect supervision, and means controlled by the operatorfor causing said connector to restore to normal.

4. In a telephone system, a calling line, a finder switch adapted tofind said line, a trunk line extending to an operators position, meansresponsive to the initiation of said call for operating said finder tofind said line, means responsive when said line is found for connectingthe line to said trunk line, means responsive to the connection of saidtrunk line with said subscribers line for signalling the operator, meanscontrolled by the operator for transmitting ringing current over saidtrunk line, a relay responsive to said ringing current, and meanscontrolled by said relay for transmitting said ringing current over saidcalling line to signal the subscriber connected thereto.

5. In a telephone system as claimed in claim 4, in which the callingline may be further connected with a called line, and in which the relayinitially operated to control the application of ringing current to thecalling line is subsequently operated to control the application ofringing current to the called line.

6. In a telephone system, a trunk line extending from a manual exchangeto a second exchange, a storage battery in the second exchange, circuitconnections for charging said battery over said trunk line from astorage battery in said manual exchange, and a charge control rheostatincluded in said circuit for regulating the current flow from the manualexchange battery to said second exchange battery.

"7. In a telephone system, a trunk line extending from a manual exchangeto a second exchange adapted to be used for talking purposes, a storagebattery in said second exchange, circuit connections for charging saidbattery over said trunk line from a storage battery in said manualexchange, a charge control rheostat included in said circuit forregulating the current flow from the manual exchange battery to saidsecond exchange battery, means included in said circuit operatedresponsive to the seizure of said trunk line by a subscriber in saidsecond exchange for disconnecting the charging circuit, and means insaid manual exchange operated responsive thereto for signalling theoperator at the manual exchange.

8. In a telephone system, a subscribers line, a line relay for said lineadapted to be operated over a circuit including an operating Windingbridged across the line when the subscriber initiates a call, to lockitself over a locking winding and to disconnect the operating windingfrom across the line, a finder switch for extending said subscribersline to an operators position, con-- Eacts on said relay for marking thesubscribers line in the bank of said finder and for completing a circuitfor operating the finder to find the marked line, and means operatedwhen the marked line is found for shunting the locking winding of saidrelay thereby releasing the relay and again connecting the operatingwinding across the line.

9. In a telephone system, a subscribers line, a line relay for said lineadapted to be operated over a circuit including an operating windingbridged across the line when the subscriber initiates a call, to lockitself .over a locking winding and to disconnect the operating windingfrom across said subscribers line, a trunk line, a switch operative forextending said subscribers line to said trunk line, means controlled bythe ener gization of said relay for operating said switch to connect thesubscribers line to said trunk line, and means operated in response tosaid connection for deenergizing said relay to again connect theoperating winding of said relay across the subscribers line.

10. In a telephone system, a subscribers line, a trunk line, a linerelay individual to the subscribers line, means controlled by thesubscriber in initiating a call for energizing said relay, 2. lockingcircuit for maintaining said relay energized after the subscriberreplaces his receiver in case the trunk line is busy, a switch operatedin response to the trunk line becoming idle for connecting thesubscribers line to said trunk line, and means responsive to saidconnection for deenergizing said relay.

11. In a telephone system, a subscribers line, a trunk line, a linerelay individual to the subscribers line, means controlled by thesubscriber in initiating a call for energizing said relay, a lockingcircuit for maintaining said relay energized after the subscriberreplaces his receiver in case the trunk line is busy, a switch operatedin response to the trunk line becoming idle for connecting thesubscribers line to said trunk line, means responsive to said connectionfor deenergizing said relay, and means for signalling the subscriber toinform him that-his call may be further extended.

12. In a telephone system, a calling line, a called line, afinder-connector link circuit for connecting said lines, an alternatingcurrent relay in said link circuit, said relay operated iresponsive tothe application of ringing current to said link circuit, meanscontrolled by said relay for connecting a branch circuit over which theringing current is transmitted over the called line to signal the calledsubscriber, and meansin said link circuit for transmitting an inducedring-back tone in the calling line in response to the application ofsaid ringing current to the link circuit.

13. In a telephone system, a subscribers line, a line relay having anoperating winding and a locking winding, said relay energized over itsoperating winding and locked energized over its locking winding inresponse to the subscriber initiating a call, an automatic switch, acircuit closed in response to the connection of said switch to said lineto shunt said locking winding to deenergize said relay, said relayenergized over its operating winding and locked energized over itslocking winding in response to the application of ringing current tosaid line when it is a called line, and another circuit closed to shuntsaid locking winding to deenergize said relay when ringing current isdisconnected from said line.

14. In a telephone system, subscribers lines, a line relay individual toeach subscribers line, each of said relays energized and lockedenergized in response to the subscribers on such lines initiating acall, a connector switch having access to said lines, wipers on saidconnector switch operated from normal position over said lines toconnect with a called one of said lines, a normally closed circuit insaid connector switch including one of said wipers, means for releasingsaid connector switch after operation by operating the wipers over saidlines to normal position, and a relay operated during the restoringoperation of the connector switch to open said normally closed circuitto prevent the deenergization of any of the relays which were lockedenergized in initiating a call.

15. In a telephone system, a calling line, a called line, afinder-connector link for connecting said lines, means responsive to thecalling party initiating a call for operating said finder of the link toconnect the calling line to said link, means for directively operatingthe'connector of the link to connect with the called line, analternating current relay in said link oper ated in response to theapplication of ringing current to said link circuit, means operated inresponse to the operation of said relay in case only the finder has beenoperated for connecting said ringing current to the calling line, andmeans operated in response to the operation of said relay in case theconnector has been operated for connecting said ringing current to thecalled line.

16. In a telephone system, a first exchange, subscribers lines in saidexchange, a second exchange, a trunk line comprising only two conductorsconnecting said exchanges, a connector switch in said first exchangehaving access to said subscribers lines, said connector switch operatedover said trunk line from the second exchange to connect a callingsubscriber in the first exchange connected to said trunk line to acalled subscriber in the same exchange, a relay in said switch operatedin response to either subscriber transmitting a disconnect signal,contacts operated by said relay opening one of the conductors of saidtrunk line, a relay in the second exchange operated responsive to theopening of said one conductor, and supervisory means at the secondexchange operated by said last relay.

1'7. In a telephone system, a calling line, a called line, afinder-connector link operative for connecting said lines, analternating current relay in said link operated in response to theapplication of ringing current to said link circuit, and means operatedby said relay for connecting said ringing current to either the callingor the called line dependent upon whether the connector of said link isoperated at the time of the application of said ringing current.

18. In a telephone system, a calling line, a called line, afinder-connector link for connecting said lines, said finder operated inresponse to the initiation of a call on said calling line to find andconnect with such calling line, a trunk line terminating said link, saidconnector operated over said trunk line to connect with said calledline, and a single ringing key connecting ringing current to said trunkline when operated to ring either the calling subscriber or the calledsubscriber dependent upon whether the connector is operated at the timeof the connection of ringing current to said trunk line.

19. In a telephone system, a first and a second exchange, a trunk lineconnecting said exchanges, a storage battery in the first exchange,circuit connections for charging said battery over said trunk line froma source of current in the second exchange when the trunk line is idle,a relay at each end of said trunk line normally energized by saidcharging current, means responsive to the seizure of said trunk line atthe second exchange for opening said circuit connections to deener'gizesaid normally energized relays, a second relay in the first exchangeoperated to open a further point in said circuit connections and tocondition said trunk line for use in establishing a telephone connectionin response to the deenergization of the relay in the first exchange,and a delay device operated a predetermined time after the seizure ofsaid trunk line in response to said seizure to further condition saidtrunk line for telephonic use.

20. In a telephone system, a first and a second exchange, a trunk linecomprising only two conductors connecting said exchanges, and circuitcombinations arranged to transmit charging current over the twoconductors in parallel when the trunk line is idle, to transmit impulsesover only one of said conductors when extending a telephone connection,to transmit ringing current over the other of said conductors forsignalling purposes, and to supervise an established connection over thesaid other conductor.

EDl/VARD S. PETERSON.

